Conventional methods for synthesizing chiral aminoepoxides (e.g. the compounds of formulae 6 or 8, shown in FIGS. 2 and 3), using chiral amino acids and their derivatives as starting materials, are well known (Chem. Rev. 2006, 106, 2811-2827). Several general synthetic strategies for preparing α-amino epoxides are reported, including erythro selective chloromethylation of phenylalaninal derivatives; erythro selective reduction of halomethyl ketones (see U.S. Pat. No. 6,683,214 and EP 1 050 532); direct reduction of α-amino aldehydes by sulfonium ylides; epoxidation of allylamines; and reductive amination of keto epoxides. Nonetheless, in most of these cases, only one of the diastereomers (erythro or threo) is available.
Thus, there exists an unmet need for methods providing key precursors that can be easily converted to both erythro and threo chiral aminoepoxides from easily available starting materials. The present invention addresses this and other needs.